Breeding-induced changes in the rhizosphere microbial communities in Lima bean (Phaseolus lunatus)

Lima bean (Phaseolus lunatus L.) breeding aims to select more productive and uniform plant varieties, impacting various plant traits, including root characters. Changes in root traits have repercussions on the rhizosphere, thereby influencing the composition of rhizospheric microbial communities. In this study, we assessed the structure and composition of the microbial community through 16S rRNA sequencing to compare the rhizosphere of different genotypes during lima bean breeding. Specifically, we compared the rhizospheric microbial communities of two parents (P1 - UFPI 628 and P2 – G25276, from Brazil and Argentina, respectively) and their segregation generations (F₂ and F₇). The microbial richness and diversity remained consistent across all genotypes, while the structure of the microbial community differed between parents (P₁ and P₂) and the advanced lineage (F₇). We observed genotype-specific enrichment of bacterial groups, indicating a nuanced interaction between lima bean genotypes and microbial communities. Moreover, segregating generations exhibited unique enrichment of bacterial families associated with plant growth promotion, such as Pedosphaeraceae (F₂) and Xanthobacteraceae (F₇). Analysis of microbial interactions revealed an alteration in network complexity, with advanced lineages, particularly F₇, displaying a higher number of interactions. Despite taxonomic differences across generations, functional traits remained consistent between parents and advanced lineages. These findings offer valuable insights into optimizing plant-microbe interactions to enhance lima bean yield in breeding programs. By understanding the dynamics of rhizospheric microbial communities in response to breeding efforts, we can harness beneficial interactions to improve plant performance and sustainability in agricultural systems.